Alternate history

[RalfJung]

This is an alternative version of recent Miri history where #2554 never got merged. We will probably have to force-push Miri to this branch to resolve the subtree sync issues.

[RalfJung]

The github diff is wrong (?!?), the actual git diff origin/master is smaller:

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 253aa3a8..a88e6911 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -275,28 +275,3 @@ see <https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html>.
 
 With this, you should now have a working development setup! See
 [above](#building-and-testing-miri) for how to proceed working on Miri.
-
-
-### Fetching the latest changes from the rustc repo
-
-Run the josh proxy locally
-
-```
-docker run -p 8000:8000 -e JOSH_REMOTE=https://github.com -v josh-vol:/data/git joshproject/josh-proxy:latest
-```
-
-Register the josh proxy as a remote
-
-```
-git remote add josh http://localhost:8000/rust-lang/rust.git:/src/tools/miri.git
-```
-
-Fetch (takes ca 5-10 min the first time)
-
-```
-git fetch josh
-git checkout josh/master
-git switch -c josh_sync
-```
-
-Now push `josh_sync` to your own miri fork and open a PR with it.
diff --git a/cargo-miri/src/main.rs b/cargo-miri/src/main.rs
index c43bf0bf..9b5fa7ae 100644
--- a/cargo-miri/src/main.rs
+++ b/cargo-miri/src/main.rs
@@ -1,4 +1,3 @@
-#![cfg_attr(bootstrap, feature(let_else))]
 #![allow(clippy::useless_format, clippy::derive_partial_eq_without_eq, rustc::internal)]
 
 #[macro_use]
diff --git a/rust-version b/rust-version
index a9318667..78b9a110 100644
--- a/rust-version
+++ b/rust-version
@@ -1 +1 @@
-744e397d8855f7da87d70aa8d0bd9e0f5f0b51a1
+acb8934fd57b3c2740c4abac0a5728c2c9b1423b
diff --git a/src/lib.rs b/src/lib.rs
index 7b7178fd..bf4e2131 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,7 +10,6 @@
 #![feature(is_some_with)]
 #![feature(nonzero_ops)]
 #![feature(local_key_cell_methods)]
-#![cfg_attr(bootstrap, feature(let_else))]
 // Configure clippy and other lints
 #![allow(
     clippy::collapsible_else_if,
diff --git a/tests/fail/concurrency/windows_join_detached.stderr b/tests/fail/concurrency/windows_join_detached.stderr
index 20f34cf1..78c75611 100644
--- a/tests/fail/concurrency/windows_join_detached.stderr
+++ b/tests/fail/concurrency/windows_join_detached.stderr
@@ -8,7 +8,7 @@ LL |         let rc = unsafe { c::WaitForSingleObject(self.handle.as_raw_handle(
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE:
    = note: inside `std::sys::PLATFORM::thread::Thread::join` at RUSTLIB/std/src/sys/PLATFORM/thread.rs:LL:CC
-   = note: inside `std::thread::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/mod.rs:LL:CC
+   = note: inside `std::thread::JoinInner::<()>::join` at RUSTLIB/std/src/thread/mod.rs:LL:CC
    = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/mod.rs:LL:CC
 note: inside `main` at $DIR/windows_join_detached.rs:LL:CC
   --> $DIR/windows_join_detached.rs:LL:CC
diff --git a/tests/fail/erroneous_const2.stderr b/tests/fail/erroneous_const2.stderr
index 4d402257..05ed8ea1 100644
--- a/tests/fail/erroneous_const2.stderr
+++ b/tests/fail/erroneous_const2.stderr
@@ -4,9 +4,9 @@ error: any use of this value will cause an error
 LL | const FOO: u32 = [X - Y, Y - X][(X < Y) as usize];
    | --------------    ^^^^^ attempt to compute `5_u32 - 6_u32`, which would overflow
    |
+   = note: `#[deny(const_err)]` on by default
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
-   = note: `#[deny(const_err)]` on by default
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/erroneous_const2.rs:LL:CC
diff --git a/tests/fail/invalid_bool.rs b/tests/fail/invalid_bool.rs
index fe9bb3be..525f8831 100644
--- a/tests/fail/invalid_bool.rs
+++ b/tests/fail/invalid_bool.rs
@@ -1,6 +1,7 @@
 // Validation makes this fail in the wrong place
 // Make sure we find these even with many checks disabled.
 //@compile-flags: -Zmiri-disable-alignment-check -Zmiri-disable-stacked-borrows -Zmiri-disable-validation
+#![feature(bench_black_box)]
 
 fn main() {
     let b = unsafe { std::mem::transmute::<u8, bool>(2) };
diff --git a/tests/pass/float.rs b/tests/pass/float.rs
index ce62fb0d..48dd9944 100644
--- a/tests/pass/float.rs
+++ b/tests/pass/float.rs
@@ -1,4 +1,4 @@
-#![feature(stmt_expr_attributes)]
+#![feature(stmt_expr_attributes, bench_black_box)]
 #![allow(arithmetic_overflow)]
 use std::fmt::Debug;
 use std::hint::black_box;
diff --git a/tests/pass/issues/issue-miri-2433.rs b/tests/pass/issues/issue-miri-2433.rs
deleted file mode 100644
index a8281d30..00000000
--- a/tests/pass/issues/issue-miri-2433.rs
+++ /dev/null
@@ -1,24 +0,0 @@
-#![feature(type_alias_impl_trait)]
-
-trait T {
-    type Item;
-}
-
-type Alias<'a> = impl T<Item = &'a ()>;
-
-struct S;
-impl<'a> T for &'a S {
-    type Item = &'a ();
-}
-
-fn filter_positive<'a>() -> Alias<'a> {
-    &S
-}
-
-fn with_positive(fun: impl Fn(Alias<'_>)) {
-    fun(filter_positive());
-}
-
-fn main() {
-    with_positive(|_| ());
-}
diff --git a/tests/pass/u128.rs b/tests/pass/u128.rs
index 6def529d..0ef7a514 100644
--- a/tests/pass/u128.rs
+++ b/tests/pass/u128.rs
@@ -1,3 +1,4 @@
+#![feature(bench_black_box)]
 use std::hint::black_box as b;
 
 fn main() {

Those are the synced changes from the rustc repo, and a docs change that was part of #2554, so this is all expected.